The present invention relates to an extra magnetic field positioning apparatus in an optical magnetic disk apparatus.
A stepping motor, having several stable points in the motor itself, has sometimes been used as a drive motor for an extra magnetic field positioning apparatus in an optical magnetic disk apparatus.
However, since the dumping factor of the stepping motor used for driving is bad in the extra magnetic field positioning apparatus of the optical magnetic disk apparatus of the prior art, a longer setting time is required for positioning. Moreover positioning accuracy is lowered by fluctuation in the magnetic field of said stepping motor at the respective stable points for the positioning. Further, there has been a problem that it is very difficult to stop the stepping motor at the desired angle between said stable points, because said stable points of the stepping motor are set with equal intervals.